We excite ZnO samples with two-cycle optical pulses directly from a mode-locked oscillator with average powers of several tens of milliwatts. The emitted light reveals peaks at the carrier-envelope offset frequency fø and at 2fø in the radio-frequency spectra. These peaks can still be detected in layers as thin as 350 nm—a step toward determining the carrier-envelope offset phase itself.
© 2002 Optical Society of America
O. D. Mücke, T. Tritschler, M. Wegener, U. Morgner, and F. X. Kärtner, "Determining the carrier-envelope offset frequency of 5-fs pulses with extreme nonlinear optics in ZnO," Opt. Lett. 27, 2127-2129 (2002)